Basic Capacitor Formulas
I. Capacitance (farads)
XI. Equivalent Series Resistance (ohms)
.224 K A
E.S.R. = (D.F.) (Xc) = (D.F.) / (2 π fC)
English: C =
TD
XII. Power Loss (watts)
.0884 K A
2
Metric: C =
Power Loss = (2 π fCV ) (D.F.)
TD
XIII. KVA (Kilowatts)
II. Energy stored in capacitors (Joules, watt - sec)
-3
2
KVA = 2 π fCV x 10
2
1
E = ⁄
2
CV
XIV. Temperature Characteristic (ppm/°C)
III. Linear charge of a capacitor (Amperes)
6
Ct – C25
C25 (Tt – 25)
dV
dt
T.C. =
x 10
I = C
XV. Cap Drift (%)
IV. Total Impedance of a capacitor (ohms)
C1 – C2
C1
2
2
ͱ
C.D. =
x 100
Z = RS + (X - X )
C
L
V. Capacitive Reactance (ohms)
XVI. Reliability of Ceramic Capacitors
1
x =
c
L0
Lt
Vt
Vo
X
Tt
To
Y
=
2 π fC
( ) ( )
VI. Inductive Reactance (ohms)
XVII. Capacitors in Series (current the same)
xL = 2 π fL
Any Number:
1
C
1
1
C2
1
---
=
+
VII. Phase Angles:
C1
C
N
T
Ideal Capacitors: Current leads voltage 90°
Ideal Inductors: Current lags voltage 90°
Ideal Resistors: Current in phase with voltage
C1 C2
C1 + C2
Two: C =
T
XVIII. Capacitors in Parallel (voltage the same)
VIII. Dissipation Factor (%)
C = C1 + C2 --- + C
T
N
E.S.R.
D.F.= tan ␦ (loss angle) =
= (2 πfC) (E.S.R.)
X
XIX. Aging Rate
c
IX. Power Factor (%)
A.R. = %D C/decade of time
P.F. = Sine ␦ (loss angle) = Cos (phase angle)
P.F. = (when less than 10%) = DF
f
XX. Decibels
db = 20 log
V1
V2
X. Quality Factor (dimensionless)
1
D.F.
Q = Cotan ␦ (loss angle) =
METRIC PREFIXES SYMBOLS
-12
K
A
TD
V
t
= Dielectric Constant
= Area
f
= frequency
= Inductance
= Loss angle
= Phase angle
Lt
= Test life
Pico
Nano
Micro
Milli
Deci
Deca
Kilo
Mega
Giga
Tera
X 10
X 10
X 10
X 10
X 10
X 10
X 10
X 10
X 10
X 10
-9
L
␦
Vt
Vo
Tt
= Test voltage
-6
-3
= Dielectric thickness
= Voltage
= Operating voltage
= Test temperature
= Operating temperature
-1
+1
+3
+6
+9
+12
f
= time
X & Y = exponent effect of voltage and temp.
To
R
= Series Resistance
Lo
= Operating life
s
2
KYOCERA AVX [ KYOCERA AVX ]
